I just wanted to add I bought one today and it is lag city. I typically only play FaceBook games and even those stutter and beachball.
Beachballin' all over the place.
Edit: needless to say this is going back tomorrow. Completely unacceptable. Two minutes to boot from powered off is ridiculous.
Did you pull up Activity Monitor? Last time I checked, any new machine has to go thru indexing by Spotlight and thus can really make a spinning hard drive suck until it is complete.
Maybe this has changed, but then again I'm all SSD over here so it doesn't bother me. My guess is that if you had let the indexing complete, then your Mini would have run a lot better. Indexing a spinning drive is really taxing until it is complete and when Spotlight is searching the entire drive, you can imagine how awful that can make things.